feat: add canonical Experiment foundation

AGENTS.md

@@ -253,6 +253,7 @@ not open the PR against the fork unless the user explicitly asks you to.
 |----------|-------------|
 | [docs/architecture/overview.md](docs/architecture/overview.md) | System architecture, component interactions, data flow |
 | [docs/architecture/app-design.md](docs/architecture/app-design.md) | Data models, API design, package dependency graph |
+| [docs/architecture/experiments.md](docs/architecture/experiments.md) | Canonical Experiment revisions, execution attempts, fixed-vector storage, publication, and client contract |
 | [docs/architecture/prompt-evaluations.md](docs/architecture/prompt-evaluations.md) | Static prompt quality, datasets, commands, and maintenance rules |
 | [docs/architecture/data-organization-projects.md](docs/architecture/data-organization-projects.md) | Projects (a single container) to isolate/group data within a cluster; composes with data-tags and auth-rbac |
 | [docs/architecture/auth-rbac.md](docs/architecture/auth-rbac.md) | Explicit-login IdP auth, Redis user-access cache, Portal handshake; deferred RBAC/internal-token roadmap |